Self-locking pedestal drafting table



Nov. 18,- 1958 A. MARTl 2,860,938

SELF-LOCKING PEDESTAL DRAFTING TABLE Filed Nov. 21, 1956 2 Sheets-Sheet 1 3: 17:12:11 LI Z Nov. 18, 1958 A. MART! SELF-LOCKING PEDESTAL DRAFTING TABLE 2 Sheets-Sheet 2 Filed Nov. 21, 1956 A .m 1 8 m. m NN 2 3 3 m n \W ow m a \\W\\ vyvwgvvwwyw w United States Patent O '"ice 2,860,938 SELF-LOCKING PEDESTAL DRAFTING TABLE Arnold Marti, Zurich, Switzerland, assignor to Bureautechnik A. G., Zurich, Switzerland Application November 21, 1956, Serial No. 623,674

Claims priority, application Switzerland November 23, 1955 4 Claims. (Cl. 31136) The invention relates to drawing boards provided with a central pillar. This central pillar has to be rather heavy and must have a wide standing area in order to give the necessary stabilityto the board. Consequently it is not quite easy to turn the board when it is desired to orientate the drawing board differently e. g. in view of varying illumination. Repeatedly sliding the pillar on the floor may also damage the latter. Moreover with conventional drawing boards of this kind the board proper is arranged at a certain level, which forces the user to always assume the same position when drawing.

The present invention has for its main object to overcomethese disadvantages, whereby the board proper is mounted on a vertical pillar which is adjustable in height and is rotatable 360 relative to the base of .the pillar.

This and other objects and features of my invention will be clearly understood from the following description of an embodiment thereof given by way of example with reference to the accompanying drawings in which:

Fig. 1 is a side elevation of the drawing board;

Fig. 2 shows a detail of Fig. 1 on a larger scale;

Fig. 3 is a section on the line III-III of Fig. l.

The central pillar of the drawing board illustrated has a circular base 1 of large standing area. On this base a pedestal 2 is rotatably journalled by means of a circle of rollers 3. With the rotatable pedestal 2 a tube 4 is fixedly connected which forms a guide for a column 5 likewise formed by a tube on which the board proper 6 is mounted in a manner to be described later in more detail. The column can only be shifted but not turned in the tube 4.

The column 5 can be adjusted in height by means of a conventional hydraulic device by operating a lever 7. By stepping on this lever in the direction of the arrow 8, a certain amount of oil is pumped by the pump of said hydraulic device into a lifting jack thereof, and thereby the column 5 is raised a certain amount. For lowering the column 5, it is only necessary to release some pressure fluid from the cylinder of the hydraulic device by pressing a button 9 controlling a conventional drain valve.

To enable the pedestal 2 and with it column 5 to be turned to a desired position, the pedestal 2 can be detached from and fixed on the base 1 by means of a lever 10.

A connecting piece between the rotatable pedestal 2 and the guide tube 4 is denoted 11. A closure ring 12 is fixed on the tube 4 by means of screws 13. A key 15 connected to this ring by means of a screw 14 engages in a groove 16 of the column 5 and thereby prevents any turning of the column 5 in the tube 4.

On the upper end of the vertical column adjustable in height, a bearing bracket 17 is mounted and fixedly attached by means of a screw 18. In this bearing bracket a bushing 19 is mounted eccentrically on a shaft 20 which is in turn eccentrically mounted in this bearing bracket. This shaft is also journaled in a second bearing bracket 21. This second bearing bracket 21 is fixed to the board 6 proper, for example by means of screws (not shown).

5, which is 2,860,938 Patented Nov. 18 1 958 The bushing 19 is connected for rotation to the shaft 20 by means of a key 22 which is'fixed thereto by means of screws 23, while a screw 24, which is too weak for transmitting the torque, merely secures the axial position of the shaft and of the bushing.

Two round discs 25 are fixedly attached to the first bearing bracket 17 by means of screws 26 (one of which only is shown), and the shaft 20 also passes eccentrically through them.

The shaft 20 is fixedly connected by means of a coupling member 27 to one end of a shaft '28, the other end of which is bent up and forms a lever 29. The coupling member 27 is pinned at 30 to the shaft 20 where -it has a small shoulder, and is screwed and pinned to the shaft 28 at 31, 32, respectively. The shaft 28 is also journalled in the bearing 33 fixed to the board 6 proper.

On the coupling member 27 a lever 34 is fixedly arranged, the end of which is connected at 36 by a strong tension spring 35 to the second bearing bracket 21, so that a torque is applied to the two coupled shafts 20 and 28 in the sense of the arrow 37.

The second bearing bracket is provided with a halfcylindrical shell 38, the inner radius of which is slightly larger than the outer radius of the discs 25 on which this shell rests at 39 and 40 (Fig. 3) in the position illustrated.

The components 27 and 33-36 have been omitted in Figs. 1 and 2 for clarity.

The device described operates as follows:

When shaft 20, and-with it he bushing 19yfixedly mounted on it, turns in the sense of the arrow under the action of the spring 35, the thinnest part of the bushing due to the eccentricity thereof moves into a low position, which causes a lowering of the shaft 20. The bushing 19 and the discs 25 are so dimensioned and disposed that the shell 38 rests on the said discs 25 before the thinnest part of the bushing 19 is in the lowest position. In that position shown in Figs. 2 and 3 the shell 38 is firmly pressed against the discs 25 by the action of the spring which tends to turn the shaft 20 further on, so that the friction produced thereby prevents the bearing bracket 21 from turning about the shaft 20.

In order to vary the slope of the board proper, the shaft 20 is turned in the direction opposite to that of the arrow 37 by means of the lever 29. Thereby a thicker portion of the bushing 19 is moved into the low position, which causes the shaft 20 to be raised and consequently the shell 38 to be freed from pressure on the discs 25. Subsequently the board proper can be inclined at will within very wide limits. After rebasing the lever 29 the board proper is immediately automatically fixed in its new position in the manner described hereinabove.

In order to increase the friction between the components 25 and 38 these components may be provided on their contacting surfaces with serrations or with a friction lining.

While I have herein described and illustrated in the accompanying drawings what may be considered a typical and particularly useful embodiment of my invention, I wish it to be understood that I do not limit myself to the particular details and dimensions described and illustrated, for obvious modifications will occur to a person skilled in the art.

What I claim as my invention and desire to secure by Letters Patent, is:

1. A pedestal drafting table comprising a bearing bracket mounted on top of a board column supporting a board, a horizontal shaft eccentrically journalled in said bearing bracket, the board proper being mounted pivotally about said horizontal shaft, a spring attached both to said eccentrically journalled shaft and to said bearing bracket and tending to bias said shaft into a low position relative to said bearing bracket, a brake component fixedly connected to said column, and a brake component fixedly connected-to-said board proper, the said two brake components-being forced against one another by the biasing action of said spring, whereby the slope of said board proper is automatically fixed.

2. A pedestal draftingtable comprising abearing bracket mountedon' top of a board column supporting aboard, ahorizontal shaft eccentrically-journalled in said bearing bracket, the board proper being mounted pivotally-about said horizontal shaft, a spring attached both to-said eccentrically journalled shaft and to said bearing bracket and tending to bias said-shaft into a low position relative to said bearing bracket, abrake component fixedly connected to said column, a brake component fixedlyconnected to said board proper, the said two brake components being forced against one another by the biasing action of said spring, whereby the slope of said board proper is automatically fixed, and a lever fixed to said shaft and adaptedto turn same in the opposite direction to the bias of said spring, whereby to release the "braking action of said two brake components and allow the slope of said board proper to be varied. I

3. A pedestal draftingtable comprising a first bearing bracket mounted on top of a board column supporting a board, a horizontal shaft eccentrically journalled in said bearing bracket, the board proper being mounted pivotally about said horizontal shaft, a spring attached both to said eccentrically journalled shaft and to said bearing bracket and tending tosbias said shaft into a low position relative to saidzbe'aring bracket, a brake component fixedly connected to said column, and a brake component fixedly connected to said board proper, one'of said brake components having a second bearing bracket and a semi-cylindrical shell attached to said board proper associated with .said second bearing bracket, :and the otherofsaid brake components comprising two discs fixedly connected to said-first bearingbracket on said column, 'the saidtwo brake components being forced against one another by the biasing action of said spring, whereby the slope of said board proper is automatically fixed.

4. A pedestal drafting table comprising a bearing bracket mounted on top of a board column supporting a board, a horizontal shaft eccentrically journalled in said bearing bracket, the board proper being mounted pivotally about said horizontal shaft, a spring attached both to said eccentrically journalled shaft and to said bearing bracket and tending to bias said shaft into a low position relative to said bearing bracket, a second shaft arranged in alignment with the first-named shaft and coupled thereto by a coupling member, said second shaft having one end bentup to form an operating lever, a lever arm fixedly mounted on said coupling member, said spring having one end thereof attached to said leverrarm, a brake component fixedly connected to said column, and a brake component fixedly connected to said board proper, the said two brake components being forced against one another by the biasing action of said spring, whereby the slope of said board proper is automatically fixed.

ReferencesCited in the file of this patent UNITED STATES PATENTS 915,418 Dexter Mar. 16, 1909 1,373,473 Weydell Apr. 5,,1921 2,601,998 Murray .July 1, 1952 2,605,156 Laxo Iuly29, 1952 FOREIGN PATENTS 12,226 Great Britain ,1915 

